Press tool



S. E. LOFTS PRESS TOOL July 14, I936.

Filed Aug. 23, 1935 Patented July 14, 1936 PRESS root.

Sidney Edward Lofts, Ewell, England .,This invention relates. tqpresstools for forming the sheet.;meta1-ends of-cans or: like containers; i-The invention is concerned with the formation ofican ends which areprovided on the inner or outer" surface with a score. which facilitatesopeningv of the ,can,-the material: adjacent the score beingstrengthened by a rib. I Usually the score is; continuousiorexample in acircular form, and a reinforcement is-ipirovided. on the inside of;thescore to strengthen'th'e material which is to be-removed when the can'is opened.

.Insome cases, thescore is not continuous soxas to leave anuncut=portion to. serve as a hinge for the part which is to be opened;

--In forming such-can ends it is the practice to first forma bead forreinforcing purposes duped by such a subsequent operation. f

It has been found that a can end produced by scoring a. blank providedwith a bead; as hereinbefore described I is not satisfactory for easyopening and that it is-necessary that the bead should be distorted, soas, to. provide arib which ncl n d t wards the scorethus pr ducin i thepreferred form a doublethickness of? metal close tothe scorewhich willenable the material of the can-end within the score tojibe easilyremoved Without buckling. g y

rAn biett f the present inv ntion s to vide mproved press t l ior ermi ican nd u h'a s o e nd f rc ileir blank ovide with a b ad.

- T nv n i n a o d n y comp ises. a p es tool for forming can ends 'fronblanks provided with a b comnr s natwoi -o r ins 10.0

*parts which ar pr v d d o ra in l m n s for produ a sc r adia nt o thheadand witlioth c -qp ra e m nt f distorting the head to produceareinforcing rib c o e t he score by m an of a. in p ration iofgthe'onetool., 1

Th nce-operati lemen s f he 991. for

formin t e co usua ly-compri e cor edge on one'too l partsand aco=operating--flat surface on the othert ool partpand heretofore consderable ,difficuit has: been encountered n producing satisfactoryscores; mainlydueto the permitted tolerance as regards; the thickness ofa any iv n standa d au mater a u h a 0 mercial tin plate. Although thevariation in thiekness is relatively small it has serious efiectsofi'tlfienature' of the score produced. It has been found in practicethat when the press is set to produce the correct score in a sheet ofaccurate thickness, not only is the material left at the score less fora relatively thin sheet than for a relatively thick sheet, but also thedepth of the score is greater for the thinner sheet; thus accentuatin'gthe difference in thickness of the material at the score for thedifierentthicknesses of sheet. By the thickness of material at the scoreI mean the distance between the deepest partof the incision and theopposite surface of the sheet.

Now the thickness of material at the score is a most importantconsideration -in the final product as any slight departure from apredetermined thickness at this point may render the productunsatisfactory. If this thickness istoo small the product is weakened-toa serious extent"whereas if it is toolarge-the score is not adequate'for its -purpose of permitting easy opening of thecontainer. Anotherobject of the presentinvention is to provide a press tool wherebyentirely satisfactory scores 'canbeproduced' irrespective ofany'variatiorisin the thick;- ness of the -'material and hence to avoidwaste of the material now resulting from the production of so manyunsatisfactory products.

According 'to a further feature-of the-present invention there isprovided a press tool for'producing scores in sheet metal wherein 'thetool parts are provided with cO-operating stopmem' bers to determine theminimum separation of the tool partsand the thickness of material at thescore. By this means the thickness of 'the 'material at the score ismaintained'constant Figure 4" is'asimilar view of the'final can end.

Referring to the drawing, the top'tool' part comprises a block I 0,adapted to be carried'in the movable part of the press, and a ringmemberH mounted within a housing l2 secured in' this block by meansof studs isalso provided.

The bottom tool shown in Figure 2 comprises a base {5 adapted tobesecured to the bed-plate of the press andcarries the lower toolpartwhich comprises a scoring ring t6 and a deforming member I? whichco-operate respectivelywith the flat inner surface l8 a'nd theSinnersurface I9 of the ring member H. The bottom tool also comprises apressure pad 20, and surrounding the scoring ring it, a pressure ring2|, the pad and they :are treated in parts in operation. The contactingsurface of" thestop member 25 is preferably formed with grooves 21 toensure close contact of this stop.

member with the surface 26 of the top tool.

I claim:

1. A press tool for forming can ends from blanks having a bead,comprising two cooperating'tool members which are provided'with coop-'erating parts for producing a' score adjacent to the bead and with othercooperating parts spaced M respectively from said scoring partsaccording to proximity of the score to the bead, for distorting V Theconstruction of the blank which 15170 form the can end is shown inFigure 3 and is provided with a bead 3|! of circular form, and inaddition with a flanged part 3| whioh'is to form the means of securingthe can end to the-body of the can. This blank is fed on to the pressurepad and the top tool is then-brought down on to the blank. The pressurepad [4 of the top tool first makes contact with the blank-and, inconjunction with the pressure 'pad- 20 serves to hold theblank inposition. The lower annular surface of the housing !2 engages withtheflange M of the blank and, in conjunction with the inclined surface28 of the stop member 25, turns up the end of the an of the blank toforce this bead outwardly towards the score in order to form thereinforcing ridge 35. The deforming part' I! of the bottom tool isinclined inthe direction to ensurethat the bead shall be forcedoutwardly towards the score, and preferably the co-operating surface ofthe top' tool is ofcomplementary shape.

The'stop member. and the co-operating stop surface 26 are so formed withregard to the tool parts that when these stop membersare brought"into-contact the scoring edge of the ring I6 is "separated from thecooperating surface N3 of thetop tool part by a distance predeterminedto provide the required thickness of material at the score. The stopmembers thus'positivelycontrol the thickness of material at the score inthe blanks produced by the press tool'regardless of variations inthickness of the. material, and thus theproducts which are obtained areall uniform .in this respect.

It will be understood that the under surface of the can end as shown inFigures 3 and 4,is intended to be on theoutside when the can end issubsequently joined to the bodyof the can, and the can ends are shown inthis position because the, inverted position in the tool.

The surface l9 of the top tool may be cut away to provide a clearancespace, the deforming action being effected by the part ll of the bottomtool. Furthermore, the stop members may be modified in form, for examplethey may be formed in'one with the respectivetool parts themselves andalso instead of being annular members they may be of any other desiredform depending for instance on the'shape of the blank. It is preferable,however, to make the contacting surfaces of the surrounding members of afairly large area in order to minimize the wear which takes placebetween the co-operating parts of the tool.

thebead to provide a reinforcing rib closeto the said score by meansof asingle operation of the one tool for each blank.

2. .A .press tool for forming can ends from blanks having a bead,comprising two cooperating tool members which are provided with twocooperating scoring parts for producing a score in the blank adjacent tothe bead and with two cooperating forming parts spaced respectively fromsaid'scoring parts according to proximity of the score to the bead,fordistorting the bead to'provide-a reinforcing rib close to the score f inone operation of the tool, at least one of said forming partsbeinginclined in the direction to deform the bead towards thescore.

V 3. A I press tool-for forming in one operation 7 can ends from blanksprovided with a bead, com- .prising a tool member having a scoring edgefor producinga score in the blank adjacent to the bead'nandflan innerpressure part spaced, from' said scoring edge according to the proximityof the score to the bead, for distorting the bead to provide areinforcing rib close to the score,

and a cooperating tool member having a pressure part cooperatingwithsaid scoring edge in form- .ing the score.

- 4. A'press tool for forming in one operation can-ends from blanksprovided with a bead comprising a tool member'having a scoring edge forproducing a score in the blank at the outer side Y of .the bead, and apressure part internally of the scoring edge to engage the bead andinclined in the direction to distort the bead outwardly to- -member todistort the bead outwardlyin the direction of the score.

5. A press toolfor forming in one operation can ends from blanksprovided with a bead, com- Y prising a tool member having a scoring edgefor producing ascore in the blank at the outer side.

of the bead, a pressure part internally of the scoring edge to engagethe bead and inclined in the direction to distortthe bead outwardlytowards the score,'a stop member surrounding and rigid with said toolmember, a cooperating toolme'me ber comprising an abutmentsupporting'theblank against pressure applied by the scoring edge of the other toolmember, a pressure part complementary with the pressure part of theother tool member to distort the bead outwardly in the direction of thescore, and a stop membersurrounding and rigid with said cooperating toolIi member, which stop members abut in the operation of the tool todetermine the minimum separation of the scoring edge from thecooperating abutment of the other tool member in order. to

' control the thickness of the material at the 'deep-' estpart of thescore. 7

' SIDNEY EDWARD LQFTS.

